I have a small PCB created in Altium. It has flex and rigid parts.
My problem is when I try to change the board shape ("Design-> Board Shape-> Define board shape from selected objects"), I got the below error on the corner (45 mm, 25 mm). On that corner there are 3 junctions, 2 lines, and 1 arc connected, it seems normal, and I don't understand the problem. How can I solve this?
Panels can be created in a non-panel design by leaving non-zero-width webs between regions. This is manufacturable as such (well, given some more considerations, i.e., use actual mousebites or whatever). If you like, the webs can be made zero width by also cutting them with a Board Cutout Region of the same dimension.
Example (AD16):
There are three board areas in this design; they are joined by thin traces which draw the board outline. Two such traces and one cutout region are selected, and (partially) shown in List for reference.
Somewhat surprisingly, 3D view shows no web between them, but apparently the side walls correctly cancel each other out.
To create this outline, select the outermost perimeter, D, S, D (Design / Board Shape / Define from selected objects), then place board cutouts in the remaining regions (here, the wide areas between outline sides).
As you can see, the fabricator figured out the correct intent given the data and labeling, and chose an arrangement suitable for their process (as instructed).
(Disclosure: the 7-transistor is my logo.)
I don't know if this is the kind of thing you're going for specifically, but it shows one realization (from EDA design to fabrication) of the technique.
When you create the board shape you can have an outline but it can't overlap and it must be continuous. Altium is letting you know at that location (48mm,25mm) that the outline is either not continuous or there is Gap.
You can't create a board outline with a triple junction.
You should create a board outline out of one continuous shape and if you need to cut out go to board create cut out and create the cutout out out of an inner shape which also must be continuous.
It also looks like you have two thin strips of PCB to another section, that will probably break the DRC rules of wherever get your PCB manufactured. Most board houses have a minimum thickness check the minimum thickness after board manufacturer and make a thin connector of that width
